The present invention relates to an optical data recording device for recording data, such as date, optically in a photographed frame on a photo filmstrip, and a camera with the optical data recording device, wherein the camera includes a lens-fitted photo film unit that does not allow the user to load a filmstrip.
A camera comprising an optical data recording device for optically recording date data, like the date and time of photography, on a filmstrip has been known. It is desirable to introduce the optical data recording device into a lens-fitted photo film unit, hereinafter referred to as a film unit, wherein an unexposed photo filmstrip is previously loaded in a unit body that has simple photographic mechanisms incorporated therein. In one type of the optical data recording device, data is recorded from a front or emulsion side of the photo filmstrip. In another type of the optical data recording device, data is recorded from a rear or base side of the photo filmstrip. In either type, the date data is ordinary recorded in a position slightly displaced from a corner toward a center.
In the type where data is recorded from the rear side of the photo filmstrip, a display panel, e.g. an LCD panel, that displays data to record, e.g. the date of photography, as transparent characters is placed in proximity to the rear side of the photo filmstrip. The display panel is illuminated from the rear side in synchronism with activation of a shutter, so light travelling through the display panel is directly used for recording data in the photographed frame. Another kind of this type uses a display panel that is constituted of light emitting diodes or the like, to record data in the photographed frame by projecting light directly from the light emitting diodes. This type does not need any optical system for forming an image of the displayed content on the display panel onto the photo filmstrip.
However, because the optical data recording device of this type comprises the display panel and the lamp for illuminating the display panel, and must be provided on a rear lid of the camera or on a rear cover of the film unit, it has a disadvantage of making the camera or the film unit thicker. Beside that, for synchronizing the data recording with the photographing, it is necessary to interconnect the optical data recording device with those circuits and mechanisms which are located on the front side of the photo filmstrip, though the optical data recording device is located on the rear side of the photo filmstrip. So the number of parts is increased, and wiring between these parts needs complicated manufacturing processes or increased number of processes, thereby increasing the cost of manufacture.
On the other hand, in the type where data is recorded from the front side of the photo filmstrip, an projection lens is placed between the display panel and the emulsion surface of the photo filmstrip, to project an image of data displayed on the display panel onto the photo filmstrip. Because the projection lens is used, and also a sufficient space is provided between the display panel and the photo filmstrip by virtue of the thickness of the camera body, it is possible to record a sharp image of the data.
As an optical data recording device of the type where data is photographed from the front side of the photo filmstrip, there is one that suggested by the present applicant (Japanese Patent Application No. 9-141249). This data recording device is provided with a shutter aperture for data that is located near a shutter aperture for photography, through which subject light is conducted to the photo filmstrip, and a display panel and an projection lens are placed before and behind the shutter aperture for data. The shutter aperture for data is opened and closed by a data shutter member that is formed integrally with a shutter blade for the shutter aperture for photography. According to this configuration, it is possible to record data as displayed on the display panel optically onto the photo filmstrip by projecting light traveling through the display panel through the projection lens onto the filmstrip, while the shutter aperture for data is opened in synchronism with the photography.
Among presently marketed cameras, there are ones that permit designating a print size at the photography so that photo prints of different aspect ratios may be obtained from frames photographed on the same photo filmstrip. One method of designating the print size is actually changing the exposure area on the photo filmstrip by switching a print size switching member. Another method of designating the print size is optically recording a corresponding mark to the designated print size onto the filmstrip outside the exposure area of a constant size, wherein the photographed frame is trimmed for printing. To record date data optically at a proper position for the designated print size, it is necessary to change the position to project the date data in cooperation with the change in print size. In the conventional data recording device, data display position on the display panel is shifted relative to the projection lens, or a switching mirror is provided between the projection lens and the photo filmstrip to adjust the projecting position by changing the angle of the switching mirror. However, these switching mechanisms for the optical data recording device are so complicated and requires so much mounting space and accuracy that it has been hard to turn them to practical use.
In the Advanced Photo System (APS) that has recently been put into practice and marketed, the photo filmstrip and the camera permit producing photo prints of different aspect ratios from that of a standard size frame, though all frames are photographed in the standard size, by recording magnetic data for each individual frame to designate an aspect ratio of photo prints on a transparent magnetic recording layer that is formed on the base side of the filmstrip. In the APS, a standard exposure area or standard size frame on the photo filmstrip has the same aspect ratio as a hi-vision (H) size photo print (89xc3x97158 mm), so a conventional (C) size photo print (89xc3x97127 mm) is produced from a photograph area that is obtained by restricting the standard size frame from left and right, i.e. in a lengthwise direction of the frame, whereas a panoramic (P) size photo print (89xc3x97254 mm) is produced from a photograph area that is obtained by restricting the standard size frame from top and bottom, i.e. in a widthwise direction of the frame. It is to be noted that the lengthwise direction of the frame is identical to the lengthwise direction of the filmstrip.
The camera of the APS may also records data such as the date of photography magnetically on the magnetic recording layer of the photo filmstrip, so the data may be read out on the printing to print the data at a designated position on a photo print. For the magnetic recording, however, a magnetic head and a circuit for driving and controlling the magnetic head are needed. These elements are so expensive that it is practically impossible to introduce the magnetic recording function to low-price cameras or the film units.
In the APS, insofar as the exposure area through the taking lens is fixed to be the standard frame size, it is possible to select any one of the print sizes: H, P and C sizes, after the photography, for example at the time of ordering photo prints, even though the pictures are photographed through such a camera or a film unit that does not permit switching the print size at the photography, e.g. those specific to the C size. For the sake of printing the data, such as the date of photography, within the photo print even when the C size print is designated, it is necessary to optically record the data within the corresponding area to the C size, called C size frame area, of the standard frame.
As described above, the left and right margins of the C size frame area is located closer to an optical axis of the taking lens, in comparison with the left and right margins of the standard frame or H size frame area. Therefore, in order to record the data within the C size frame area by use of the optical data recording device where the data is recorded by the light projected from the front side of the photo filmstrip through the projection lens and the data shutter aperture, it is necessary to put the projection lens closer to the center of the frame, because the center of the recorded data is put on the optical axis of the projection lens. In that case, since the taking lens is designed to expose the H size frame area, the projection lens, a lens holder for the projection lens or other member would shade a marginal portion of the H size frame area from the light from the taking lens.
If the data shutter aperture is placed closer to the shutter aperture for photography so as not block the subject light path, it would arise a problem that the data shutter member on the way to opening and closing the data shutter aperture would move in front of the shutter aperture for photography, so the photographed subject image would have unevenly exposed portions.
Meanwhile, since the low-price cameras and the film units use a simple and cheap taking lens, some of those hold the photo filmstrip behind the taking lens such that the filmstrip is curved with its concave oriented to the taking lens in correspondence with the curvature of field of the taking lens, in order to correct the curvature of field for photographing a subject image.
If the above method of recording data from the front of the photo filmstrip is introduced into the camera or the film unit that compensates for the image distortion by curving the photo filmstrip, an image of the display panel, i.e. optically recorded data, would be partly blurred unless an image surface of the display panel that is formed through the projection lens is aligned with the curved surface of the photo filmstrip.
In view of the foregoing, an object of the present invention is to provide an optical data recording device that records data, such as date, inside a photographed frame, by projecting light from the front of the photo film, and makes it possible to locate the data recording position closer to the optical axis of the taking lens without blocking the light path from the taking lens.
Another object of the present invention is to provide an optical data recording device that is simple in construction and can change the data recording position on the filmstrip.
The present invention further has an object to provide a camera with an optical data recording device that is simple in construction, cooperates with a print size switching operation and changes the data recording position on the filmstrip in accordance with the selected print size, wherein the camera includes not only those allowing the user to load the film, but also the film unit.
To achieve the above objects, in an optical data recording device for recording data, as displayed on a display panel, optically in a photographic frame on a photo filmstrip through a projection lens, wherein the photographic frame has an image of a subject photographed therein through a taking lens, the present invention is in that the display panel and the projection lens are located on the side of the taking lens relative to the photo filmstrip, and that a center of the display panel is displaced from an optical axis of the projection lens in a direction away from an optical axis of the taking lens, such that the data on the display panel is projected onto the photo filmstrip to be recorded at a position that is shifted from the projection lens optical axis toward the taking lens optical axis.
According to the optical data recording device of the present invention, the data is optically recorded at a closer position to the taking lens optical axis without the need for placing the projection lens closer to the taking lens optical axis, even where the data is projected from the front of the photo filmstrip. Therefore, if the H size photo print or the C size photo print is selected, it is possible to record the photographic date in the photo print, while preventing the subject light for recording the subject image from being blocked by the projection lens or other elements.
According to a preferred embodiment of the present invention, a stop is provided between the display panel and the projection lens, such that the following condition is satisfied:
1 greater than d/fxe2x89xa70.3|R1| greater than |R2|xc3x973
wherein f represents the focal length of the projection lens, d represents a distance from the stop to an image side surface of the projection lens, R1 represents a radius of curvature of a surface of the projection lens on the side of the display panel, and R2 represents a radius of curvature of the image side surface of the projection lens.
Adjusting a relationship between the focal length of the projection lens and the distance from the stop to the image side surface of the projection, and a relationship between the respective radiuses of curvature of the opposite surfaces of the projection lens in the above ranges makes it possible to form the image of the display panel, i.e. the data, adequately on the photo filmstrip.
Furthermore, it is possible to improve compactness while keeping good quality of the image of the display panel formed through the projection lens, by defining an angle xcex8 of a line that extends from a farther edge of the display panel from the projection lens optical axis to a center of the stop, relative to the projection lens optical axis, to satisfy the following condition:
0 less than xcex8 less than 0.55
wherein the angle xcex8 is given by an equation xcex8=TANxe2x88x921 {(Q+L/2)/S}, assuming that S represents a distance from the display panel to the stop, L represents a longer side length of the display panel, and Q represents an amount of displacement of the center of the display panel from the optical axis of the projection lens.
Assuming that F1 represents the f-number of the taking lens, and F2 represents the f-number of the image forming lens, the f-numbers preferably satisfy the following condition:
log2 (F2)xe2x89xa6log2 (F1).
In this way, the exposure level through the projection lens is set higher in comparison with exposure conditions of the taking lens. This makes it possible to record the data or the image of the display panel on the photo filmstrip at a sufficient exposure amount even with the ambient light.
Where the data is to be recorded on the photo filmstrip that is held in a curved posture, the display panel is incline to a perpendicular plane to the projection lens optical axis, such that the image surface of the display panel is formed on the photo filmstrip in parallel with its curve. Therefore, the data is recorded entirely good focusing condition on the photo filmstrip.
Where the data is to be recorded on the photo filmstrip that is held in a curved posture, it is possible to incline the projection lens optical axis to the taking lens optical axis for forming the image surface of the display panel on the photo filmstrip in parallel with its curve. Then, it becomes possible to set the display panel substantially parallel to the perpendicular plane to the taking lens optical axis. For instance, since the display panel may be set parallel to an external covering surface of a camera that is approximately parallel to this perpendicular surface, this configuration contributes to reducing useless space.
By holding the projection lens to be able to rotate about a rotary center that is displaced from its optical axis, data recording position may be relocated with economical and simple constitutions. By causing the projection lens for the data recording to rotate in cooperation with the print size switching operation mechanism, the data may be recorded at the position suitable for the selected print size. Moreover, where the photo filmstrip is held curved in the exposure position, the light path length adjusting plate for adjusting the light path length is inserted into between the display panel and the projection lens in cooperation with the projection lens being rotated, so the data may be recorded in proper focus.